Who is Matthew Garner in Among the Hidden by Margaret Haddix?

Matthew Garner is Like's oldest brother. Both Matthew and Mark sometimes resent the restrictions placed upon their own lives due to Luke's presence.... they cannot entertain friends at home.... a level of secrecy must always be adhered to.... stuff that might really get on a teenager's nerves. None-the-less, Matthew's love is evident in the time he spends with Luke at home.